$ { {3} \times \left[\begin{array}{rrr}{4} & {0} & {2} \\ {0} & {4} & {1}\end{array}\right] = {?} } $
Explanation: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rrr}{3}\times{4} & {3}\times{0} & {3}\times{2} \\ {3}\times{0} & {3}\times{4} & {3}\times{1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rrr}{12} & {0} & {6} \\ {0} & {12} & {3}\end{array}\right]}$